Wedge actuated cutting and/or forming tools

ABSTRACT

A wedge actuated cutting and/or forming tool comprises a frame including spaced guide portions. A fixed platen is mounted on the frame and a movable platen is mounted on the guide portions of the frame for reciprocation toward and away from the fixed platen. A wedge is supported for lateral reciprocation with respect to a backup and thereby effects reciprocation of the movable platen. The wedge is driven by a hydraulic cylinder and switch means are provided for regulating both the separation between the movable platen and the fixed platen at the closest point and the total stroke of the movable platen. The frame further includes a hydraulic reservoir which receives a substantial quantity of hydraulic fluid. By this means the structure of the reservoir and the hydraulic fluid therein tend to stabalize the tool and dampen vibrations caused by the operation thereof.

This is a division of application Ser. No. 331,237, filed Feb. 9, 1973.

BACKGROUND AND SUMMARY OF THE INVENTION

This invention relates to wedge-operated cutting and/or forming tools,and more particularly to an improved wedge-type drive system useful invarious types of power presses.

By definition, power presses comprise apparatus for reciprocating a toolholder or platen in a work area. This motion is typically utilized tomove a first tool mounted on the movable platen toward and away from asecond tool mounted on a fixed platen. By this means various operationsare carried out, including piercing, shearing, blanking, bending,forming, and related operations.

Various specific types of power presses have also become recognized inthe art. Thus, a shear is a power press that is specifically designed tocut strip materials to length. To this end shears are almost universallyadapted to move a pair of cutting blades passed one another and therebyeffect cutting. Typically, structure is also provided for preventingseparation of the cutting blades during the cutting operation.

As opposed to a shear, a press brake is a power press adapted to performbending and related forming operations. The tools or dies used in pressbrakes typically do not pass one another, so that structure forpreventing separation between the tools is not required. On the otherhand, the extent of separation between the tools at the closest pointshould be variable if the press brake is to have general utility.

A punch press is a type of power press adapted to perform a broaderrange of operations than is a shear or a press brake. To this end, punchpresses typically incorporate structure to provide very precise controlover the positioning of tools or dies throughout the reciprocatorycycle, as well as structure for varying the relative positioning of thetools at the closest point. One very common use of punch presses is inperforming blanking and forming operations. Punch presses are also oftenutilized to perform various combinations of piercing, shearing,blanking, and forming operations, which may be carried out eithersimultaneously or progressively.

Heretofore most power presses have comprised a motor adapted to rotate aflywheel continuously. The flywheel is selectively coupled to aneccentric by means of a dog clutch, and the eccentric is in turnconnected to a movable platen by a connecting rod. The press is actuatedby tripping the dog clutch, whereby the eccentric is coupled to theflywheel for rotation through a single revolution. By this means theeccentric and the connecting rod operate to reciprocate the movableplaten toward and away from a fixed platen.

At the present time the foregoing design is almost universally utilizedin the manufacture of power presses. However, notwithstanding widespreadusage, a number of major problems have been recognized in the design.For example, although the distance between the movable and the fixedplaten at the closest point can be varied by adjusting the effectivelength of the connecting rod, the overall stroke of the movable platencannot be changed without changing the eccentric of the press. The cycletime of the press also cannot be varied without changing substantiallythe entire structure thereof.

Another disadvantage is that once the clutch is tripped, the press mustcomplete an operating cycle before the movement of the movable platencan be terminated. This is highly undesirable, both from a safetystandpoint and from the standpoint of the possibility of damage to avery expensive set of tools should a foreign object become positionedtherebetween. Perhaps the most important disadvantage to the eccentricand connecting rod type of power press is that the apparatus is veryexpensive to purchase. This high initial cost has literally preventedthe use of shears, press brakes, and other types of power presses invarious diverse types of small businesses.

The present invention comprises a novel drive system for power presseswhich overcomes the foregoing and other disadvantages long associatedwith the prior art. In accordance with the broader aspects of theinvention, a wedge is supported for reciprocation by a fluid poweredcylinder. The wedge is provided with a camming surface which engages acooperating camming surface to effect reciprocation of a movable platen.By this means the wedge is adapted for actuation by the cylinder to movethe movable platen toward and away from a fixed platen.

The use of the present invention provides numerous advantages over theprior art. Thus, power presses incorporating the invention may bemanufactured for sale at less than one-half the price of eccentric andconnecting rod power presses of similar capacity. Structure may beprovided for varying both the overall length of and the terminal pointsof the stroke of the fluid powered cylinder. By this means not only theseparation between the movable platen and the fixed platen at theclosest point, but also the length of the stroke of the movable platenmay be easily adjusted. Finally, the stroke of the fluid poweredcylinder may be terminated at any time, regardless of whether or not anoperating cycle has been completed. This is highly advantageous bothfrom an occupational safety standpoint and from the standpoint of theability to prevent damage to tools or dies which are actuated by thepress.

In accordance with more specific aspects of the invention, the pressfurther comprises a frame including guide portions which support themovable platen for reciprocation. The fixed platen extends between theguide portion to define one end of the work area. A backup is alsoprovided for cooperation with the wedge to effect reciprocation of themovable platen under the action of the fluid powered cylinder.

The fluid powered cylinder preferably comprises a hydraulic cylinder. Insuch a case the press incorporates a self-contained hydraulic systemincluding a hydraulic reservoir comprising part of the frame of thepress. By this means the reservoir and the hydraulic fluid therein tendto add strength and rigidity to the frame, and tend to absorb vibrationswhich otherwise might be encountered during the operation thereof.

The hydraulic system further includes a pump which is driven by anelectric motor. A solenoid controlled valve is provided for regulatingthe effective stroke of the hydraulic cylinder. The solenoid controlledvalve is in turn operated under the control of switch structure which isresponsive to reciprocation of the wedge and/or the movable platen. Bythis means complete control over the separation between the fixed andmovable platens at the closest point and over the overall stroke of themovable platen is provided. A relief valve is also provided forterminating flow of hydraulic fluid to the hydraulic cylinder in theevent that the movable platen becomes stalled. By this means anypossibility of damage to the tools or dies actuated by the press iscompletely eliminated.

DESCRIPTION OF THE DRAWINGS

A more complete understanding of the invention may be had by referringto the following Detailed Description when taken in conjunction with theaccompanying Drawings, wherein:

FIG. 1 is a rear perspective view of a shear incorporating theinvention;

FIG. 2 is a front perspective view of the shear;

FIG. 3 is an illustration of the stroke control apparatus of the shear;

FIG. 4 is a perspective view of a press brake incorporating theinvention;

FIG. 5 is an illustration of the valve structure of the press brake;

FIG. 6 is a front view of a punch press incorporating the invention; and

FIG. 7 is a side view of the punch press.

DETAILED DESCRIPTION

Referring now to the Drawings, and particularly to FIGS. 1 and 2thereof, there is shown a shear 10 comprising the first embodiment ofthe invention. The shear 10 includes a frame 12 comprising a base 14 anda pair of risers 16 and 18 extending upwardly therefrom. A fixed platen20 is secured to and extends between the risers 16 and 18. A lowercutting blade 22 is secured to the fixed platen 20 by means of aplurality of bolts 24. This permits removal of the blade 22 forsharpening and/or replacement.

The frame 12 of the shear 10 further includes a pair of guide portions26 and 28 which extend upwardly from the fixed platen 20. A backup 30 issecured to and extends between the upper ends of the guide portions 26and 28. There is thus defined a work area 32 which is enclosed by thefixed platen 20, the guide portions 26 and 28 and the backup 30 of theframe 12 of the shear 10.

A movable platen 34 is slidably supported on the guide portions 26 and28 of the frame 12 for reciprocation in the work area 32 toward and awayfrom the fixed platen 20. The movable platen 34 supports an uppercutting blade 36 which is secured to the platen 34 by means of aplurality of bolts 38. This permits the blade 36 to be removed from theplaten 34 for sharpening and/or replacement.

Those skilled in the art will appreciate the fact that the function ofthe shear 10 is to cut metal and other tough materials. During suchoperations the blades 22 and 36 of the shear 10 tend to separate orspread in the direction extending mutually perpendicularly to the bladesand the reciprocation thereof. To this end the guide portions 26 and 28of the frame 12 are provided with reinforced portions 40. The functionof the reinforced portions 40 is to prevent separation of the blades 22and 36 and thereby insure a clean cut during each actuation of the shear10.

A bar 42 is secured to and extends transversely between the reinforcedportions 40 of the frame 12. A block 44 is secured to the movable platen34 of the shear 10 by means of a plurality of bolts 46. Two or morebolts 48 are threadedly engaged with the block 44 and extend throughapertures formed in the bar 42. The bolts 48 are provided with heads 50,and two or more compression springs 52 are mounted between the heads 50of the bolts 48 and the bar 42. The springs 52 therefore tend to urgethe movable platen 34 upwardly in the work area 32, whereby a gap isnormally maintained between the blades 22 and 36 of the shear 10.

A wedge 54 is mounted between backup 30 and the movable platen 34 forlateral reciprocation to effect reciprocation of the movable platentoward and away from the fixed platen. The wedge 54 includes a surface56 which is slidably engaged with a corresponding surface 58 on thebackup 30. The wedge 54 further includes an angularly extending cammingsurface 60 which mates with a corresponding surface 62 on the movableplaten 34. It will thus be understood that upon movement of the wedge 54to the right (FIG. 1), the movable platen 34 is reciprocated downwardlyagainst the action of the springs 52. Strips 63 comprising anon-metallic, low friction, pressure resistant material are positionedbetween the surfaces 56 and 58 and between the surfaces 60 and 62 tofacilitate reciprocation of the wedge 54.

The wedge 54 is operated by a hydraulic cylinder 64. The hydrauliccylinder 64 includes a framework 66 which is mounted on the frame 12 anda barrel 68 which receives a piston (not shown). A piston rod 70 isconnected between the piston of the hydraulic cylinder 64 and the wedge54. Thus, upon reciprocation of the piston in the barrel 68, the wedge54 is reciprocated with respect to the backup 30 and the movable platen34.

Referring now to FIG. 2, the shear 10 further includes a self-containedhydraulic system 72 for operating the hydraulic cylinder 64. Thehydraulic system 72 includes a hydraulic reservoir 74 which is mountedon and secured to the base 14 of the frame 12. The reservoir 74 includesa substantial quantity of hydraulic fluid, whereby the reservoir 74 andthe hydraulic fluid therein add substantial strength and rigidity to theframe 12. Furthermore, the hydraulic fluid contained in the reservoirtends to dampen vibrations which might otherwise occur due to theoperation of the shear 10.

The hydraulic system 72 further includes a hydraulic pump 76 which isdriven by an electric motor 78. Electric current for operating the motor78 is supplied through a junction box 80 and a motor control unit 82.The unit 82 includes an off-on switch 84 and other conventional controlapparatus.

The hydraulic pump 76 functions to withdraw hydraulic fluid from thereservoir 74 and to supply pressurized hydraulic fluid to a relief valve86 and a solenoid operated valve 88. The valve 88 functions under thecontrol of a treadle switch 90 to control the flow of hydraulic fluid tothe hydraulic cylinder 64. Thus, whenever the treadle switch 90 istripped, the valve 88 directs hydraulic fluid to the blind end of thecylinder 64 and thereby actuates the cylinder to reciprocate the wedge54 to the right (FIG. 1). Rightward movement of the wedge 54 in turncauses downward reciprocation of the movable platen 34 against theaction of the springs 52. After the wedge 54 has been reciprocatedrightwardly through a predetermined stroke, the valve 88 directshydraulic fluid to the rod end of the hydraulic cylinder 64. By thismeans the cylinder 64 is actuated to reciprocate the wedge 54 to theleft (FIG. 1). This in turn permits upward reciprocation of the movableplaten 34 under the action of the springs 52.

The stroke of the movable platen 34 of the shear 10 is regulated by astroke control apparatus 92. As is best shown in FIGS. 1 and 3, thestroke control apparatus 92 includes a bar 94 which is supported on thewedge 54 for reciprocation therewith. The bar 94 in turn supports a pairof switch actuators 96 and 98. A pair of limit switches 100 and 102 aresupported on the backup 30 for actuation by the switch actuators 96 and98, respectively. The switches 100 and 102 are connected to the valve 88of the hydraulic system 72 by electrical leads extending through aconduit 104.

Downward reciprocation of the movable platen 34 is regulated by thelimit switch 100 and the switch actuator 96. Thus, whenever the switchactuator 96 engages the limit switch 100, the valve 88 is actuated toterminate rightward reciprocation of the wedge 54 and to initiateleftward reciprocation thereof. Conversely, upward reciprocation of themovable platen 34 is controlled by the limit switch 102 and the switchactuator 98. Thus, whenever the switch actuator 98 engages the limitswitch 102, leftward reciprocation of the wedge 54 is terminated.Typically, rightward reciprocation of the wedge 54 is not immediatelyreinitiated upon termination of leftward reciprocation thereof. Instead,the treadle switch 90 must be reactuated in order to commence a newoperating cycle of the shear 10. Continuous operation of the shear 10may also be provided if required by a particular operation.

It will be appreciated that the movable platen 34 of the shear 10 has amaximum stroke which is determined by the length of the barrel 68 of thehydraulic cylinder 64. However, the stroke of the hydraulic cylinder 64as determined by the stroke control apparatus 92 generally does notcorrespond with either end of the barrel 68. Instead, the hydrauliccylinder is reciprocated through a stroke which is substantially lessthan the maximum stroke and which is defined by limits intermediate theends of the barrel 68. By this means both the upper and lower limits ofthe stroke of the movable platen 34 of the shear 10 are fullyadjustable.

It will be further understood that due to the nature of a shear, theextent of downward reciprocation of the movable platen 34 is typicallyrelatively fixed. Thus, it is merely necessary that the blades 36 and 22pass one another in order to achieve a clean cut. On the other hand, theextent of upward reciprocation of the movable platen 34 depends on thethickness of the material to be cut. It is generally desirable tominimize the extent of upward reciprocation of the movable platen 34 inorder to minimize the cycle time of the shear 10. However, in the eventa longer cycle is desired for any reason, the extent of upwardreciprocation may be increased by simply moving the switch actuator 98to the left on the bar 94.

At this point an important advantage resulting from the use of thepresent invention may be noted. The wedge 54 is designed to provide amechanical advantage of about 4:1. That is, the cutting force that isapplied by the movable platen 34 is about four times the force that isapplied to the wedge 54 by the hydraulic cylinder 64, and the length ofthe stroke of the movable platen 34 is about one quarter the length ofthe stroke of the wedge 54. This is advantageous because a smaller motorand pump and a smaller hydraulic cylinder may be utilized to produce agiven cutting force between the blades 36 and 22. At the same time thelonger stroke of the wedge 54 is utilized in the stroke controlapparatus 92 to provide more accurate control over the stroke of themovable platen 34.

Referring again to FIG. 2, spent hydraulic fluid from the hydrauliccylinder 64 and from the relief valve 86 are returned to the hydraulicfluid reservoir through a filter 106. The function of the relief valve86 is to terminate flow of hydraulic fluid to the hydraulic cylinder 64in case the movable platen 34 should become jammed. For example, if aforeign object should be lodged between the blades 36 and 22 so that thestroke of the movable platen 34 could not be completed to the extentrequired by the stroke control apparatus 92, pressure would build in theblind end of the hydraulic cylinder 64. Then, at a predeterminedpressure as determined by the setting of the relief valve 86, hydraulicfluid from the pump 76 is diverted to the reservoir 74 by the reliefvalve 86. This is highly advantageous both from a safety standpoint andin order to prevent damage to the blades 22 and 36 and to the remainingcomponents of the shear 10.

The shear 10 is further provided with a guide table 108 whereby materialto be cut is received between the blades 22 and 36. As is best shown inFIG. 1, an output guide 110 is also provided. Those skilled in the artwill appreciate the fact that the guides 108 and 110 are conventional innature and that other types of guides may be utilized in the practice ofthe invention, if desired.

Referring now to FIG. 4, there is shown a press brake 120 comprising asecond embodiment of the invention. The press brake 120 includes a frame122 having a base 124. A pair of risers 126 and 128 extend verticallyupwardly from the base 124 of the frame 122. A hydraulic fluid reservoir130 is secured to and extends between the upper ends of the risers 126and 128.

A backup 132 is supported on the frame 122 above the hydraulic fluidreservoir 130. A pair of guide members 136 and 138 extend verticallyupwardly from the backup 132. A fixed platen 140 is secured to andextends between the upper ends of the guide members 136 and 138. By thismeans there is defined a work area 142 which is surrounded by the backup132, the guide members 136 and 138, and the fixed platen 140.

A movable platen 144 is slidably supported on the guide members 136 and138 for reciprocation in the work area 142 toward and away from thefixed platen 140. The fixed platen 140 and the movable platen 144support a pair of cooperating tools or dies 146 and 148, respectively.Upon reciprocation of the movable platen 144, the tools 146 and 148 areadapted to bend or form metal bars or sheets or other materialspositioned therebetween. The tools 146 and 148 are supported on theplatens 140 and 144 by a plurality of bolts 150 so as to be readilyremovable therefrom.

A wedge 152 is positioned between the backup 32 and the movable platen144 for horizontal reciprocation with respect thereto. The wedge 152includes a substantially horizontally disposed surface 154 which mateswith a cooperating surface 156 on the movable platen 144. The wedge 152further includes an angularly extending camming surface 158 which mateswith a similar surface 160 on the backup 132. Thus, reciprocation of thewedge 152 to the right (FIG. 4) results in upward reciprocation of themovable platen 144, and reciprocation of the wedge 152 to the left (FIG.4) permits downward reciprocation of the movable platen 144 under theaction of gravity. Such reciprocation is facilitated by strips 161positioned between the surfaces 154 and 156 and between the surfaces 158and 160 and comprising a nonmetallic, low friction, pressure resistantmaterial.

The wedge 152 of the press brake 120 is actuated by a hydraulic cylinder162. The hydraulic cylinder 162 includes a barrel 164 having one endsupported by a cross brace 166. The cross brace 166 is secured to andextends between the guide members 136 and 138 of the frame 122, and thenleftwardly beyond the guide member 136 to support the hydraulic cylinder162. The hydraulic cylinder 162 further includes a piston (not shown)adapted for reciprocation within the barrel 164. The piston is connectedto the wedge 152 by a piston rod 168. It should be noted that the crossbrace 166 and the hydraulic cylinder 162 extend substantially parallelto the camming surfaces 158 and 160 of the wedge 162 and the backup 132,respectively. Thus, although the wedge 152 moves upwardly as it isreciprocated by the hydraulic cylinder 162, the motion of the wedge 152is substantially axial relative to the hydraulic cylinder.

The hydraulic cylinder 162 of the press brake 120 is actuated by aself-contained hydraulic system 170. The hydraulic system 170 includesthe hydraulic fluid reservoir 130 which is normally filled with asubstantial quantity of hydraulic fluid. By this means the structure ofthe reservoir 130 and the hydraulic fluid contained therein lendstrength and rigidity to the frame 122 of the press brake 120. Also, thehydraulic fluid in the reservoir 130 tends to dampen vibrations whichmight otherwise occur during the operation of the press brake 120.

The hydraulic system 170 further includes a pump 172 which is driven byan electric motor 174. Power for driving the motor 174 is suppliedthrough a motor control apparatus 176 including an off-on switch andother conventional control apparatus.

As is best shown in FIG. 5, the pump 172 of the hydraulic system 170functions to withdraw hydraulic fluid from the reservoir 130 and tosupply pressurized hydraulic fluid to a relief valve 178 and to asolenoid controlled valve 180. The valve 180 functions to control theflow of hydraulic fluid to the hydraulic cylinder 162, and therebycontrols the reciprocation of the wedge 152 and the movable platen 144.Thus, upon actuation of a treadle switch 182, the valve 178 actuates thecylinder 162 to reciprocate the wedge 152 to the right (FIG. 4). Thisresults in upward reciprocation of the movable platen 144. After thewedge 152 has been reciprocated rightwardly to a predetermined extent,the valve 178 actuates the hydraulic cylinder 162 to reciprocate thewedge 152 to the left (FIG. 4). This results in downward reciprocationof the movable platen 144 under the action of gravity.

The reciprocation of the wedge 152 is further regulated by a strokecontrol apparatus 184. The apparatus 184 includes a limit switch 186mounted on the wedge 152 for reciprocation therewith. A pair of switchactuators 188 and 190 are supported on the cross brace 166 of the frame122. Thus, upon actuation of the treadle switch 182, the wedge 152 isreciprocated to the right (FIG. 4) until the limit switch 186 engagesthe switch actuator 190. The direction of reciprocation of the wedge 152is thereupon immediately reversed, and the wedge 152 is reciprocated tothe left (FIG. 4) until the limit switch 186 engages the switch actuator188. At this point reciprocation of the wedge 152 is typicallyterminated pending subsequent actuation of the treadle switch 182. Itwill be appreciated, however, that continuous back and forthreciprocation of the wedge 152 may be provided, if desired.

It will be appreciated that in the case of a press brake, the separationbetween the fixed platen and the movable platen at the closest pointmust be adjusted in accordance with particular requirements. The lengthof the stroke of the movable platen is also preferably adjustable so asto accommodate stock of various sizes and to regulate the cycle time ofthe press brake. To this end the positioning of both of the switchactuators 188 and 190 on the cross brace 166 is rendered readilyadjustable whereby the adjustment of the press brake 120 to provideparticular stroke parameters as may be required by a particular job isprovided. As was the case with the shear 10, the limits of thereciprocations of the wedge 152 and the movable platen 144 as determinedby the switch actuators 188 and 190 typically do not correspond to thelimits of the stroke of the hydraulic cylinder 152 as determined by thephysical dimensions of the barrel 164.

As is best shown in FIG. 5, the relief valve 178 and the valve 180return spent hydraulic fluid directly to the reservoir 130 through portsextending through the risers 126. The function of the relief valve 178is to prevent damage to the hydraulic system 170 in the event of anoverload condition. For example, if a foreign object should bepositioned between the tools 146 and 148 so that the wedge 152 could notcomplete a full stroke as determined by the stroke control apparatus184, pressure would build in the hydraulic system 170. However, as soonas the setting of the relief valve 178 is reached, further hydraulicfluid from the pump 172 is returned directly to the reservoir 130. Bythis means damage to the tools 146 and 148 due to excessive forceimposed thereon is prevented.

The press brake 120 further includes a pair of guides 192 and 194mounted on opposite sides of the movable platen 144. The purpose of theguides 192 and 194 to properly position the stock between the tools 146and 148 prior to actuation of the hydraulic cylinder 162 to effectreciprocation of the wedge 152 and the movable platen 144. Aninteresting aspect of the press brake 120 is that since the guides 192and 194 are mounted on the movable platen 144, the guides arereciprocated with the movable platen. Those skilled in the art willappreciate the fact that the guides 192 and 194 are substantiallyconventional in nature and that other guide arrangements may be utilizedin the practice of the invention, if desired.

Referring now to FIGS. 6 and 7, there is shown a punch press 200comprising a third embodiment of the invention. The punch press 200includes a frame 202 comprising a base (not shown) and four legs 204extending upwardly therefrom. A fixed platen 206 is secured to andextends between the upper ends of the legs 204. A lower die 208 issupported on the fixed platen 206 of the punch press 200.

The frame 202 further includes four guide members 210 which extendupwardly from the fixed platen 206. A cylinder 212 is slidably receivedat each guide member 210, and a movable platen 214 is secured to theupper ends of the cylinders 212 by a plurality of fasteners 216. Thereis thus defined a work area 218 which is enclosed by the fixed platen206, the guide members 210, the cylinders 212, and the movable platen214.

A movable die 220 is mounted on the movable platen 214 for reciprocationin the work area 218 toward and away from the fixed die 208. As will beappreciated by those skilled in the art, the dies 208 and 220 of thepunch press 200 may be designed to perform piercing, blanking, forming,and related functions, or any combination of these functions. The dies208 and 220 may also comprise progressive dies of the type commonlyutilized in punch presses.

A backup 222 is secured to the lower ends of the cylinders 212 by aplurality of fasteners 224. A backup 222 includes a central portion 226which is reinforced by a plurality of triangularly shaped members 228. Aplurality of guide rollers 230 are mounted on the underside of thebackup 222 for engagement with the legs 204 of the frame 202.

A wedge 232 is mounted between the backup 222 and the fixed platen 206for horizontal reciprocation to effect vertical reciprocation of themovable platen 214. The wedge 232 includes a horizontally extendingsurface 234 which is slidably engaged with a corresponding surface 236of the fixed platen 206. The wedge further includes an angularlyextending camming surface 238 which mates with a corresponding surface240 on the central portion 226 of the backup 222. Strips 241 comprisinga nonmetallic, low friction, pressure resistant material are positionedbetween the surfaces 234 and 236 and between the surfaces 238 and 240.

It will thus be understood that upon reciprocation of the wedge 232 tothe left (FIG. 6) the backup 222 is reciprocated downwardly. Since thebackup 222 is connected to the movable platen 214 by the cylinders 212,this action also results in downward reciprocation of the movable platen214. Upon subsequent reciprocation of the wedge 232 to the right (FIG.6) the backup 222 is reciprocated upwardly by a small cylinder or spring242. Again, since the cylinders 212 connect the backup 222 in themovable platen 214, this action results in a corresponding upwardreciprocation of the movable platen.

The wedge 232 is operated by a hydraulic cylinder 244. The hydrauliccylinder 244 is supported on the fixed platen 206 by a framework 246,and includes a barrel 248 which receives a piston (not shown). A pistonrod (also not shown) connects the piston of the hydraulic cylinder 244to the wedge 232. Thus, upon reciprocation of the piston in the barrel248, the wedge 232 is reciprocated horizontally to effect verticalreciprocation of the movable platen 214.

The punch press 200 further includes a self-contained hydraulic systemwhich is substantially identical to the hydraulic systems 72 and 170 ofthe shear 10 and the press brake 120, respectively. An important featureof the self-contained hydraulic system comprises a hydraulic fluidreservoir comprising part of the frame 202. The reservoir receives asubstantial quantity of hydraulic fluid, whereby the structure of thereservoir and the hydraulic fluid therein add strength and rigidity tothe frame 202. Furthermore, the hydraulic fluid contained in thereservoir tends to dampen any vibrations which otherwise might occur dueto the operation of the punch press 200.

The self-contained hydraulic system of the punch press 200 functions towithdraw hydraulic fluid from the reservoir and to selectively directpressurized hydraulic fluid to the hydraulic cylinder 244. Suitablevalve structure is provided for controlling the flow of pressurizedhydraulic fluid to the hydraulic cylinder 244 and for returning spenthydraulic fluid to the hydraulic fluid reservoir. Relief valve structureis also provided for terminating the advance of the movable platen 214in the event that the pressure in the self-contained hydraulic systemexceeds a predetermined level.

The stroke of the movable platen 214 of the punch press is regulated bya stroke control apparatus 250. The stroke control apparatus 250includes a bracket 252 which is supported on one of the legs 204 of theframe 202. The bracket 252 in turn supports a pair of limit switches 256and 258. The switches 256 and 258 are positioned for actuation by thebackup 222 upon reciprocation thereof under the action of the wedge 232.The switches function to control the upper and lower limits of thestroke of the movable platen 214. By this means both the relativepositioning of the movable and fixed platens at the closest point andthe total stroke of the movable platen 214 are regulated.

Those skilled in the art will appreciate the fact that cutting and/orforming tools incorporating the present invention are adapted forworking various metals including plain carbon steel, stainless steel,aluminum, brass, etc. Various plastics, paper and paperboard products,and similar materials may also be worked with tools utilizing theinvention, if desired. It will be further understood that the cuttingblades, dies, and other tools that are utilized in the practice of theinvention are conventional in nature, and may be identical to thecorresponding tools that have heretofore been utilized in power pressesincorporating conventional designs.

The use of the invention is highly advantageous from a number ofstandpoints. Perhaps most importantly, cutting and/or forming toolsutilizing the invention may be manufactured at approximately one-halfthe cost of conventional eccentric and connecting rod presses of similarcapacity. This permits the use of tools incorporating the presentinvention in many applications wherein the use of power presses hasheretofore been prohibited due to cost considerations.

Another important advantage to the use of the invention involves thefact that control is provided, not only over the separation between themovable and fixed platens at the closest point, but also over the totalstroke of the movable platen. This affords greater flexibility in theuse of tools incorporating the invention, and also substantiallyshortens the cycle time of the movable platen in appropriateapplications.

Still another advantage to the use of the invention involves the abilityto terminate the cycle of the movable platen at any time. This isimportant not only to prevent damage to the cutting blades, dies andother tools that are utilized in conjunction with the invention, butalso from a safety standpoint.

Although preferred embodiments of the invention have been illustrated inthe accompanying Drawings and described in the foregoing DetailedDescription, it will be understood that the invention is not limited tothe embodiments disclosed, but is capable of numerous rearrangements,modifications, and substitutions of parts and elements without departingfrom the spirit of the invention.

What is claimed is:
 1. A press brake comprising:a generally verticallyextending frame including a pair of vertically extending guide portionsand a hydraulic fluid reservoir containing a substantial quantity ofhydraulic fluid, whereby the hydraulic fluid reservoir and the hydraulicfluid therein tend to stabilize the press brake and tend to absorbvibrations caused by the operation thereof; a fixed platen extendingbetween the upper ends of the guide portions of the frame and supportinga first forming tool; a movable platen slidably supported on the guideportions of the frame beneath the fixed platen and supporting a secondforming tool; a backup extending between the lower ends of the guideportions of the frame; a wedge mounted between the backup and themovable platen for lateral reciprocation with respect thereto; saidwedge and backup including cooperating camming surfaces whereby themovable platen is reciprocated toward and away from the fixed platen inresponse to lateral reciprocation of the wedge; said hydraulic fluidreservoir being positioned beneath the fixed platen, the movable platen,the backup and the wedge; a hydraulic cylinder mounted on the frame andoperatively connected to the wedge and having a predetermined maximumstroke; switch means including portions mounted on the wedge forreciprocation therewith to effect reciprocation of the hydrauliccylinder through a stroke shorter than the predetermined maximum;hydraulic pump means mounted on the frame for withdrawing hydraulicfluid from the hydraulic fluid reservoir and supplying pressurizedhydraulic fluid; and valve means for controlling the flow of pressurizedhydraulic fluid from the hydraulic fluid pump means to the hydrauliccylinder and thereby selectively reciprocating the wedge and the movableplaten.
 2. The press brake according to claim 1 wherein the pump meanscomprises a motor supported on the frame and a hydraulic pump driven bythe motor.
 3. The press brake according to claim 1 wherein the wedge isadapted to provide a mechanical advantage of about 4:1.